1. Technical Field of the Invention
The present invention relates generally to cellular wireless communication systems, and more particularly to a system and method to detect, locate and correct errors within a protocol stock to be implemented within a wireless terminal.
2. Description of Related Art
Cellular wireless communication systems support wireless communication services in many populated areas of the world. While cellular wireless communication systems were initially constructed to service voice communications, they are now called upon to support data and video (multimedia) communications as well. The demand for video and data communication services has exploded with the acceptance and widespread use of evermore capable wireless terminals and the Internet. Cellular wireless users now demand that their wireless units also support video and data communications. The demand for wireless communication will only increase with time. Thus, manufacturers of cellular wireless communication systems are currently attempting to service these burgeoning demands. As the market for wireless terminals matures and penetration rates reach saturation, manufacturers are faced with the challenge of introducing a growing number of features within shortening development timescales.
Cellular wireless networks include a “network infrastructure” that wirelessly communicates with wireless terminals within a respective service coverage area. The network infrastructure typically includes a plurality of base stations dispersed throughout the service coverage area, each of which supports wireless communications within a respective cell (or set of sectors). The base stations couple to base station controllers (BSCs), with each BSC serving a plurality of base stations. Each BSC couples to a mobile switching center (MSC). Each BSC also typically directly or indirectly couples to the Internet.
In operation, each base station communicates with a plurality of wireless terminals operating in its cell/sectors. A BSC coupled to the base station routes voice, video, data or multimedia communications between the MSC and a serving base station. The MSC then routes these communications to another MSC or to the PSTN. Typically, BSCs route data communications between a servicing base station and a packet data network that may include and couple to the Internet. Transmissions from base stations to wireless terminals are referred to as “forward link” transmissions while transmissions from wireless terminals to base stations are referred to as “reverse link” transmissions. The volume of data transmitted on the forward link typically exceeds the volume of data transmitted on the reverse link. Such is the case because data users typically issue commands to request data from data sources, e.g., web servers, and the web servers provide the data to the wireless terminals. The great number of wireless terminals communicating with a single base station forces the need to divide the forward and reverse link transmission times amongst the various wireless terminals.
Wireless links between base stations and their serviced wireless terminals typically operate according to one (or more) of a plurality of operating standards. These operating standards define the manner in which the wireless link may be allocated, setup, serviced and torn down. One popular cellular standard is the Global System for Mobile telecommunications (GSM) standard. The GSM standard, or simply GSM, is predominant in Europe and is in use around the globe. While GSM originally serviced only voice communications, it has been modified to also service data communications. GSM General Packet Radio Service (GPRS) operations and the Enhanced Data rates for GSM (or Global) Evolution (EDGE) operations coexist with GSM by sharing the channel bandwidth, slot structure, and slot timing of the GSM standard. GPRS operations and EDGE operations may also serve as migration paths for other standards as well, e.g., IS-136 and Pacific Digital Cellular (PDC).
The GSM standard specifies communications in a time divided format (in multiple channels). The GSM standard specifies a 4.615 ms frame that includes 8 slots of, each including eight slots of approximately 577 μs in duration. Each slot corresponds to a Radio Frequency (RF) burst. A normal RF burst, used to transmit information, typically includes a left side, a midamble, and a right side. The midamble typically contains a training sequence whose exact configuration depends on modulation format used. However, other types of RF bursts are known to those skilled in the art. Each set of four bursts on the forward link carry a partial link layer data block, a full link layer data block, or multiple link layer data blocks. Also included in these four bursts is control information intended for not only the wireless terminal for which the data block is intended but for other wireless terminals as well.
A wireless terminal is a complex system that requires an advanced communications protocol stack, interoperability with many network vendors' equipment and support for rich multimedia applications within the constraints of a resource-limited embedded system. Additionally, as operators begin to deploy GPSS, EDGE and 3G networks and services, users demand the latest features and applications. This in turn creates shortened product lives. This shortened product life makes the development time for new wireless terminals with the latest features, and, more importantly, the time required to obtain certification, operator approval, and mass produce the wireless terminal a key issue. The time required to develop the software for the wireless terminal is a significant part of the development time.
As new technologies such as EDGE (an evolution of GPRS) are incorporated, these technologies must be proven reliable. Otherwise, difficulties originally encountered in prior technologies will be repeated. Critical factors for software development must be met and these factors include platform quality, application integration quality and product quality. Reference designs provide a quality base on which to build a quality product.
There are three key components to wireless terminal software. These include the protocol stack, applications framework, and applications. Many consider the protocol stack to be the most complex part. However, interactions between the framework and applications are equally important.
The protocol stack implements the signaling specification and is implemented on Digital Signal Processors (DSPs) and micro controllers such as Advanced RISC Machines (ARMs). These processors execute the various CODECs, radio resource management, mobility management, call management, and data management. The application framework delivers a platform to create wireless terminals with differing functionality and applications. Three broad components to the applications framework support (1) functions and services; (2) call control; and (3) application program interfaces (APIs). The applications typically include a Wireless Application Protocol (WAP) browser for online access, a Multimedia Messaging Service (MMS) client for picture messaging and a Java 2 platform.
Previously, these complex wireless terminals have not been tested efficiently and effectively in a timely manner by relying on the end product. Also, this testing has not occurred in isolation from the GSM network. To provide adequate test coverage so that the end product can be considered ready for deployment, a complete test system and process is needed that allows testing in a timely manner.